Effect of Zhuanggu Jianxi Decoction on Synovitis in Knee Osteoarthritis Rabbits via LXRs/NF-κB Pathway

Abstract

<sec><title>Objective</title> To study the intervention effect and mechanism of Zhuanggu Jianxi decoction on synovitis in knee osteoarthritis (KOA) rabbits via the inflammatory regulation of synovial tissue and the expression of key node proteins in LXRs/NF-κB pathway. </sec><sec><title>Methods</title> Blank serum and drug-containing serum of rabbits were prepared for the intervention of synovial tissue. Twenty-two rabbits were randomly divided into two groups, with 16 in the model group and 6 in the blank group. The KOA model was injected with papain into the knee joint of the right hind limb. After the model was identified successfully, the synovial tissue of the right hind limb knee was cut into small pieces with a size about 1-2 mm³ under aseptic operation, 60 pieces were collected and randomly divided into model group, Zhuanggu Jianxi decoction group, LXRα inhibitor group and N-CoR inhibitor group with 15 pieces each, the synovial tissue pieces in each group were cultured in 6 well plates with every 3 pieces in each well, the four groups were intervened with 10% blank serum, 10% drug-containing serum, 10% drug-containing serum+5CPPSS-50 and 10% drug-containing serum+ML-792 respectively; the synovium of the blank group was prepared by the same method and cultured with 10% blank serum for 5 wells. After 7 days, synovial tissue was collected. Two wells of synovial tissue were taken from each group for HE staining, and the remaining synovial tissue was detected by Western blot and ELISA. </sec><sec><title>Results</title> 1) Morphology: compared with the blank group, HE staining in the model group showed the proliferation and disorder of synovial lining cells, a large number of inflammatory cell infiltration and fibrous tissue hyperplasia, and the morphological score was significantly increased (<italic>P</italic><0.05). Compared with the model group, mild hyperplasia and disorder of synovial lining cells, sparse scattered inflammatory cell infiltration and a small amount of fibrous tissue hyperplasia were observed in the Zhuanggu Jianxi decoction group, and the morphological score was significantly decreased (<italic>P</italic><0.05). Compared with the Zhuanggu Jianxi decoction group, the morphological score of pathological changes in the LXRα and N-CoR inhibitor groups was significantly increased (<italic>P</italic><0.05). 2) Inflammation-related indicators: compared with the blank group after intervention, the contents of IL-1β, TNF-α, MMP-3 and MMP-13 in the model group were significantly increased (<italic>P</italic><0.05); compared with the model group, the indexes above in the LXRα inhibitor group, N-CoR inhibitor group and Zhuanggu Jianxi decoction group were significantly decreased (<italic>P</italic><0.05); compared with the Zhuanggu Jianxi decoction group, the indexes above in the LXRα and N-CoR inhibitor groups were significantly increased (<italic>P</italic><0.05). Before and after intervention, the contents of IL-1β and TNF-α in the Zhuanggu Jianxi decoction group were significantly decreased (<italic>P</italic><0.05). 3) Protein expression: Compared with the blank group, the expressions of LXRα and N-CoR proteins in the model group were significantly decreased (<italic>P</italic><0.05), and the expression of P50 and P65 proteins were significantly increased (<italic>P</italic><0.05). Compared with the model group, LXRα and N-CoR protein in the LXRα inhibitor group and N-CoR protein in the N-CoR inhibitor group were not significantly decreased (<italic>P</italic>>0.05), P50 and P65 protein expression were significantly decreased (<italic>P</italic><0.05). The protein expression of LXRα and N-CoR in the Zhuanggu Jianxi decoction group were significantly increased (<italic>P</italic><0.05), and the protein expression of P50 and P65 were significantly decreased (<italic>P</italic><0.05). Compared with the Zhuanggu Jianxi decoction group, the protein expression of LXRα and N-CoR in both the LXRα and N-CoR inhibitor groups were significantly decreased (<italic>P</italic><0.05), and the protein expression of P50 and P65 were significantly increased (<italic>P</italic><0.05). </sec><sec><title>Conclusion</title> Zhuanggu Jianxi decoction could improve the pathological manifestations of synovial lining cell hyperplasia and the disorder arrangement, inflammatory cell infiltration and fibrous tissue hyperplasia, reduce the content of inflammatory related indexes in tissues, so as to reduce the inflammatory response of KOA synovial tissue in rabbits, which may be related to the up-regulation of LXRα and N-CoR protein expression in synovial cells via LXRs/NF-κB pathway in synovial tissue, thereby down-regulating P50 and P65 protein to reduce IL-1β, TNF-α, MMP-3 and MMP-13. </sec>